The present invention relates to a disk brake for a vehicle.
One example of conventional disk brakes is disclosed in Japanese Utility Model Application Public Disclosure (KOKAI) No. 5-12778 (corresponding to U.S. Pat. No. 5,299,663. The disk brake disclosed in this publication is generally characterized as follows. A cylinder block, which is provided on a caliper, is provided with an extension which extends across an inner pad, a disk, and an outer pad, and a pair of bifurcated claw portions are provided on the distal end of the extension so as to be capable of pressing the outer pad. In addition, a wear sensor is attached to the outer pad inbetween the claw portions.
The wear sensor is provided with a mounting portion which is attached to the outer pad, and a pair of vibrating pieces which extend circumferentially of the disk from the left and right ends, respectively, of the mounting portion toward the radially inward end of the outer pad along the outer surface of the outer pad. Each vibrating piece has an extended portion extending from the mounting portion, and a contact portion formed at the distal end of the extended portion in such a manner that the contact portion is bent toward the disk so as to extend around the inner edge of the outer pad as viewed radially of the disk. In this conventional disk brake, when the outer pad becomes worn to a predetermined extent, the distal ends of the contact portions come into scraping contact with the disk, causing the distal ends to vibrate. As a result, the vibrating pieces vibrate to sound an alarm, thereby informing the driver or other vehicle occupant that the outer pad has become worn.
Incidentally, in the above-described conventional disk brake, the contact portions lie in the vicinity of the inward end face of the outer pad as viewed radially of the disk. Therefore, in a case where the gap between the central cylindrical portion of the disk and the inward end face of the outer pad is extremely narrow, it may be impossible to provide the contact portions in the space therebetween and hence impossible to attach the wear sensor itself. In addition, the portion of the disk with which the distal ends of the contact portions come in contact are radially inward of a braking surface of the disk which is in contact with the outer pad. That is, the distal ends of the contact portions come in contact with a portion of the disk where rust readily accumulates because it is not swept by the outer pad. Therefore, when the distal ends of the contact portions come into scraping contact with the disk to sound an alarm, the sound pressure level of the alarm is not always stabilized because of the presence of the rust in the portion of the disk.